The photo has been used for illustrative purposes.
The UN push for a quick vaccine came a day after US President Donald Trump prompted outcry and ridicule with his suggestion that disinfectants be used to treat coronavirus patients.
Governments around the world are struggling to limit the economic devastation unleashed by the virus, which has infected nearly 2.8 million people and left half of humanity under some form of lockdown.
The scale of the coronavirus pandemic has forced medical research on the virus to move at unprecedented speed, but effective treatments are still far off and the United Nations chief said the effort will require cooperation on a global scale.
The warning suggests that the issuance of "immune passports" may promote the continued spread of the pandemic.
"We face a global public enemy like no other," UN Secretary-General Antonio Guterres told a virtual briefing on Friday, asking for international organisations, world leaders and the private sector to join the effort. "A world free of COVID-19 requires the most massive public health effort in history."
Any vaccine should be safe, affordable and available to all, Guterres said at the meeting, which was also attended by the leaders of Germany and France. But notably absent were the leaders of China, where the virus first emerged late last year, and the United States, which has accused the UN's World Health Organisation of not warning quickly enough about the original outbreak.
Across the Muslim world, hundreds of millions of faithful also opened the Ramadan under stay-at-home conditions, facing unprecedented bans on prayers in mosques and on the traditional large gatherings of families and friends to break the daily fast.
The United States is the hardest-hit country by far in the pandemic, recording more than 51,500 deaths and over 890,000 detected infections.
Britain's COVID-19 death toll passed 20,000 on Saturday in what the interior minister called "a tragic and terrible milestone" as she urged people to stay at home.
Elsewhere in Asia, authorities reported no new deaths on Saturday for the 10th straight day in China, where the virus originated.
And South Korea reported just 10 fresh cases, the eighth day in a row its daily jump came below 20. There were no new deaths for the second straight day.
A tentative easing around the world of coronavirus lockdowns gathered pace Saturday with the reopening in India of neighbourhood stores that many of the country's 1.3 billion people rely on for everything from cold drinks to mobile phone data cards.
On Sunday, Spain is to start allowing children out for up to an hour a day in the first steps towards easing one of the world's toughest lockdowns.
The measure, which comes into effect on Sunday morning, means under-14s will be able to go out once a day for one hour between 9:00am and 9:00pm.
The UN humanitarian chief Mark Lowcock told a video briefing most experts agree that the peak of the COVID-19 pandemic hasn’t reached the poorest parts of the world, but may peak in the next three to six months.
More than 8.53 million people have been reported infected by the novel coronavirus globally and 453,834 have died, a Reuters tally showed as of 1326 GMT on Friday.
Shortages of critical equipment led to fierce competition among buyers from Europe, the US and elsewhere. A regional leader in Paris described the scramble to find masks a “worldwide treasure hunt.” Gov. Andrew Cuomo warned that New York could run out of ventilators in six days.
The 36-year-old husband, from the US, told Abu Dhabi Personal Status Court that his wife, 32, had tried to take her own life and also threatened to kill their children.
Sheikha Latifa said on Instagram, “We were blessed today with a baby girl, Sheikha Bint Faisal Al Qasimi.”
Police in the western province of Makkah said the attacker was a Saudi, but it did not give the nationality of the guard, who they said had sustained minor injuries.
Christian Bolok, who was in his mid-30s, was trying to grab a rooster when one of its gaffs — small steel blades attached to a rooster's legs — cut a gaping wound on his left leg and hit his femoral artery, provincial Governor Edwin Ongchuan said.